Incidental coronary artery calcification on non-gated CT thorax correlates with risk of cardiovascular events and death

Abstract

Objectives: To assess coronary artery calcification (CAC) on non-contrast non-ECG-gated CT thorax (NC-NECG-CTT) and to evaluate its correlation with short-term risk of cardiovascular disease (CVD) events and death.

Methods: Single-institution retrospective study including all patients 40-70 years old who underwent NC-NECG-CTT over a period of 6 months. Individuals with known CVD were excluded. The presence of CAC was assessed and quantified by the Agatston score (CACS). CAC severity was defined as mild (< 100), moderate (100-400), or severe (> 400). CVD events (including CVD death, myocardial infarction, revascularisation procedures, ischaemic stroke, acute peripheral atherosclerotic ischaemia), and all-cause mortality over a median of 3.5 years were recorded. Cox proportional-hazards regression modelling was performed including CACS, age, gender and CVD risk factors (smoking, hypertension, diabetes mellitus, dyslipidaemia, and family history of CVD).

Results: Of the total 717 eligible cases, 325 (45%) had CAC. In patients without CAC, there was only one CVD event, compared to 26 CVD events including 5 deaths in patients with CAC. The presence and severity of CAC correlated with CVD events (p < 0.001). A CACS > 100 was significantly associated with both CVD events, hazard ratio (HR) 5.74, 95% confidence interval: 2.19-15.02; p < 0.001, and all-cause mortality, HR 1.7, 95% CI: 1.08-2.66; p = 0.02. Ever-smokers with CAC had a significantly higher risk for all-cause mortality compared to never-smokers (p = 0.03), but smoking status was not an independent predictor for CVD events in any subgroup category of CAC severity.

Conclusions: The presence and severity of CAC assessed on NC-NECG-CTT correlates with short-term cardiovascular events and death.

Key points: • Patients aged 40-70 years old without known CVD but with CAC on NC-NECG-CTT have a higher risk of CVD events compared to those without CAC. • CAC (Agatston) score above 100 confers a 5.7-fold increase in the risk of short-term CVD events in these patients. • The presence and severity of CAC on NC-NECG-CTT may have prognostic and therapeutic implications.

Keywords: Computed tomography; Coronary artery calcification; Preventative cardiology.

Fig. 1

Flowchart of the study cohort and overview of events. *Excluded for history of CVD: 2 ^$MI—myocardial infarction, 4 coronary artery bypass graft (CABG), 29 percutaneous coronary intervention (PCI), 2 cardiac valve interventions, 2 known ischaemic heart disease, 2 ischaemic stroke; ^aInterstitial lung disease, pulmonary haemorrhage, chronic obstructive pulmonary disease, asthma, cystic lung disease, bronchiectasis, cause for persistent cough, recurrent infection, shortness of breath; ^bSuspected lung cancer, completion staging from extrathoracic malignancy; ^cIncluding tuberculosis, atypical/fungal, allergic bronchopulmonary aspergillosis, assessment of response to antibiotics, prior to organ transplant; ^dLung volume reduction surgery, endobronchial valves, recurrent pneumothorax, foreign body and non-major trauma; ^e5 PCI and 3 CABG; ^fTAVI—transcatheter aortic valve implantation

Fig. 2

a High-resolution non-contrast non-ECG gated CT thorax (mediastinal window) of a 55-year-old male patient showing coronary artery calcification in the proximal left anterior descending (LAD) and right coronary arteries (RCA). b The same study demonstrating the calcified plaque within LAD (yellow) and RCA (red) as highlighted on the CT CaScoring on Syngo.via software together with the automatically generated table with per-vessel and total Agatston score. c In this case, the coronary artery calcification had moderate severity and placed the patient close to the 90^th percentile for matched age and gender as demonstrated by the automatically generated CT CaScoring percentile chart (Raggi, Circulation 2001). d Coronary angiography shows angiographically significant stenosis in the proximal LAD and a large obtuse marginal branch. e Chest radiograph showing LAD stent placed following myocardial infarction, three months after the reference CT

Fig. 3

Kaplan–Meier event-free survival curves for each CAC severity category and event type show that the presence and severity of CAC significantly impacts event-free progression. *CVD – cardiovascular disease; CHD – coronary heart disease